Development of microwave assisted extraction for the simultaneous determination of isoflavonoids and saponins in radix astragali by high performance liquid chromatography

A microwave assisted extraction (MAE) procedure was first developed for the simultaneous determination of isoflavonoids and astragalosides in Radix Astragali (RA). MAE showed the highest extraction efficiency when compared to Soxhlet, reflux, and ultrasonic extraction. It was found that flavonoid glycoside malonates were converted into their related glycosides during the prolonged conventional extraction, thus affecting the reproducibility. However, the conversion was inhibited when using MAE. After being optimized in terms of solvents, microwave power, and irradiation time, MAE was used for the simultaneous determination of isoflavonoids and astragalosides in RA with HPLC-UV-evaporative light scattering detection (ELSD). Our results indicated that extraction by MAE was more effective than by other conventional techniques. Moreover, the MAE method followed by HPLC-UV-ELSD determination was a simple, rapid, and reliable method for the quality assessment of RA.     

Simultaneous determination of nine flavonoids and qualitative evaluation of Herba Epimedii by high performance liquid chromatography with ultraviolet detection

A simple high performance liquid chromatographic method has been developed for the determination of nine flavonoids in Herba Epimedii, including quercetin-3-O-glucoside, epimedin A, hexandraside A, epimedin B, epimedin C, icariin, icariside I, icariside II, and icaritin. The chromatographic separation was performed on a Diamonsil C(18) column (5 microm, 250x4.6 mm) with gradient elution by acetonitrile-0.5% acetic buffer (adjusted to pH 5.00 with triethylamine). Methodological validation gave acceptable linearities (r(2) >0.9992) and recoveries (ranging from 98.9 to 102.4%). The limits of detection of these flavonoids ranged from 16.3 to 83.3 ng. The results indicated that the contents of flavonoids in Herba Epimedii varied significantly from habitat to habitat with contents ranging from 0.05 to 39.0 mg/g. Twenty five Herba Epimedii samples prepared from five different botanical materials were investigated by the established method, and the results showed the influence of the botanical material and the habitat on the quality of Herba Epimedii. The proposed method is simple, effective, and suitable for the evaluation of this traditional Chinese medicine.     

微渗析活体取样与液相色谱安培检测法联用测定鼠脑中黄嘌呤和次黄嘌呤

采用微渗析活体取样技术和高效液相色谱安培检测法 ,测定了鼠脑纹状体中的黄嘌呤和次黄嘌呤。安培检测以玻碳电极为工作电极 ,检测电位为 0 .9V。在 5 .0× 1 0 - 7～ 1 .0× 1 0 - 4 mol/L浓度范围内 ,黄嘌呤和次黄嘌呤的浓度分别与峰电流呈良好的线性关系 ,检出限分别为 8 0× 1 0 - 8mol/L和 3 0× 1 0 - 7mol/L。该方法为生命科学的研究提供了一种新的分析手段     

The determination of oxalic acid in urine by high performance liquid chromatography with electrochemical detection

A system for the determination of oxalic acid in human urine using ion exchange-ion pair, high performance liquid chromatography with electrochemical detection (HPLCEC) is described. Urine is acidified with HCl, and excess CaCl2 is added to precipitate oxalate ion. The precipitate is isolated, redissolved in dilute sulfuric acid, and separated on a strong cation exchange column using an acetic acid-solium acetate-tetrabutylammonium tetrafluoroborate mobile phase adjusted to pH 2.8. Using an electrochemical detector at 1.25 volts vs. the saturated calomel electrode (SCE), oxalic acid exhibits a linear dynamic range from 1 to 1000 mg/liter with a detection limit of 0.1 mg/liter. Quantitative data are obtained by the method of standard addition in the clinically significant range from 5 to 40 mg/liter. Percentage recovery for spiked urine samples was 97.8% with a relative standard deviation of 2.5%.     

Simultaneous determination of airborne carbamates in workplace by high performance liquid chromatography with fluorescence detection

A high performance liquid chromatography with fluorescence (HPLC-F) detector was examined to simultaneous determination of airborne carbamates in the workplace of manufactory. The OVS-2 air sampling tube filled with glass fiber filter or quartz fiber and combined filter/XAD-2 were evaluated to collect nine commonly used carbamates (Carbofuran, Isoprocarb, Methomyl, Metolcarb, Thiodicarb, Carbaryl, Oxamyl, Methiocarb, and Prpoxur) from the air of manufactory in high humidity country. After being extracted with acetonitrile from sampling tubes, the carbamates were determined by high performance liquid chromatography with fluorescence detection posterior to on-line derivatization. The collection of carbamates and the recovery of extraction from glass wool fiber in several concentration levels, and from quartz filter were evaluated. The storage stability of carbamates was also tested. Results indicated that the HPLC-fluorescence method offers satisfactory resolution and sensitivity in carbamate analysis. With the glass fiber filter and combined filter/XAD-2, the Carbofuran, Isoprocarb, Methomyl, Metolcarb, and Thiodicarb were stable for a 28-day storage test, Carbaryl and Oxamyl for 14 days, and Methiocarb and Prpoxur for 7 days. All of these pesticides were with detection limit of 3 μg m⁻³. It is suited for environmental monitoring. The airborne carbamates in different areas of the manufactory were measured.     

鸡肉中11种喹诺酮类药物多残留的高效液相色谱检测

建立了用荧光检测器同时测定11种喹诺酮类药物(包括诺氟沙星、培氟沙星、环丙沙星、恩诺沙星、氧氟沙星、达氟沙星、洛美沙星、二氟沙星、沙拉沙星、恶喹酸和氟甲喹)在鸡肉中的多残留的高效液相色谱检测方法。鸡肉样品用10%三氯乙酸-乙腈(体积比为7∶3)提取两次并稀释,随后用反相固相萃取柱净化。采用Hypersil BDS-C18色谱柱分离,以乙腈和水为流动相梯度洗脱,荧光检测器用程序编程检测波长检测。11种喹诺酮类药物标准曲线的线性范围为5～1200 μg/L,相关系数大于0.998。在高、中、低三个添加水平下的回收率为56%～119%,批内相对标准偏差为0.4%～16.1%,批间相对标准偏差为1.4%～23.0%。检出限和定量限分别为1～23 μg/kg和4～40 μg/kg。该方法快速、灵敏,达到了兽药残留检测的要求。     

Sensitive determination of cinnarizine in human plasma by high performance liquid chromatography and fluorescence detection

Summary A sensitive high performance liquid chromatographic method has been developed for the determination of cinnarizine in human plasma. Cinnarizine and clocinizine (internal standard) were extracted from acidified plasma (pH 4.7) into carbon tetrachloride and the organic layer was evaporated. The products were separated on a Microspher C18 (3 m) column, using a mixture of 0.04 % triethylamine in 0.01 M ammonium dihydrogen phosphate (NH₄H₂PO₄), pH adjusted to 4.2 with orthophosphoric acid (H₃PO₄), and acetonitrile (2080, v/v) as mobile phase, at a flow rate of 1 ml/min at 40°C. Fluorescence detection (_ex = 245 nm, _em = 310 nm) was used; the detection limit was 0.5 ng/ml under the conditions used, and the calibration curve linear in the concentration range evaluated (1–60 ng/ml). The assay has been used to measure cinnarizine concentrations in plasma after oral administration to volunteers.     

Simultaneous determination of seven triterpenoids and triterpenoid saponins in Folium llicis Purpureae by high performance liquid chromatography coupled with evaporative light scattering detection

A new HPLC coupled with evaporative light scattering detection method was established for the simultaneous determination of seven triterpenoids and triterpenoid saponins in Folium Ilicis Purpureae traditional Chinese medicinal herb derived from the leaf of Ilex purpurea, namely, 3-omicron-beta-D-glucopyranosyl (1-->2)-beta-D-[6-omicron-methyl-glucuronopyranosyl]-28-omicron-beta-D-glucopyranosyl oleanolic acid (SQ-1), pedunculoside (SQ-2), 23-hydroxytormentic acid 28-omicron-beta-D-glucopyranoside (SQ-3), 23-hydroxytormentic acid (SQ-4), rutundic acid (SQ-5), ilexoside B (SQ-6), and ursolic acid (SQ-7). The optimal chromatographic conditions were achieved on a C18 column with a linear gradient elution of mobile phase A: deionized water-isopropyl alcohol-THF-acetic acid (90:10:6:1, v/v) and B: methanol-isopropyl alcohol-THF-acetic acid (90:10:6:1, v/v) at the flow rate of 1.0 mL/min; temperature for drift tube was set at 98degreesC and nitrogen flow rate was 2.8 L/min. All calibration curves of the seven compounds showed good linear regression (r2 > 0.995) within test ranges. The developed method has good repeatability for quantitation of all analytes interested with overall intraday and interday variation of less than 4.1%. The LOD (S/N = 3) and LOQ (S/N = 10) were less than 0.13 and 0.26 microg/mL, respectively, for all analytes. The established method was successfully used to evaluate the quality of Folium Ilicis Purpureae samples of different collections.     

A reversed-phase high performance liquid chromatography coupled with resonance Rayleigh scattering detection for the determination of four tetracycline antibiotics

A new reversed-phase high performance liquid chromatography with resonance Rayleigh scattering detection (HPLC-RRS) was developed for simultaneous separation and determination of four tetracycline antibiotics (TCs). A good chromatographic separation among the compounds was achieved using a Synergi Fusion-RP column (150 mm × 4.6 mm; 4 μm) and a mobile phase consisting of methanol-acetonitrile-oxalic acid (5 mM) at the flow rate of 0.8 mL min⁻¹. Column temperature was 30 °C. The RRS signal was detected at λ_ex = λ_em = 370 nm. The recoveries of sample added standard ranged from 95.3% to 103.5%, and the relative standard deviation was below 2.79%. A detection limit of 2.12-5.12 μg mL⁻¹ was reached and a linear range was found between peak height and concentration in the range of 10.36-518.0 μg mL⁻¹ for oxytetracycline (OTC), 12.11-605.5 μg mL⁻¹ for tetracycline (TC), 11.79-589.5 μg mL⁻¹ for chlortetracycline (CTC) and 10.32-516.0 μg mL⁻¹ for doxycycline (DC). The linear regression coefficients were all above 0.999. The method has been applied successfully to the determination of OTC, TC, CTC, DC in pharmaceutical formulations and in honey. The method was simple, rapid and showed a better linear relation and high repeatability.     

Rapid and sensitive determination of beta-phenylethylamine in animal brains by high performance liquid chromatography with fluorometric detection

A reversed phase HPLC method with fluorometric detection for the analysis of beta-phenylethylamine has been developed using p-methoxyphenylethylamine as an internal standard. Two columns, containing 200 microL of Dowex 50-X8 and Amberlite CG-50 respectively, were used to prepare a fraction containing beta-phenylethylamine. The recoveries of beta-phenylethylamine and p-methoxyphenylethylamine were 53.9 +/- 9.4% and 68.1 +/- 12.4%, respectively, and elution profile of p-methoxyphenylethylamine was sufficiently well correlated with that of beta-phenylethylamine. Regional distributions of beta-phenylethylamine in rat and mouse brains were determined. The highest concentrations were found in hypothalamus and hippocampus in both animals.     

Identification and comparative determination of senkyunolide A in traditional Chinese medicinal plants Ligusticum chuanxiong and Angelica sinensis by HPLC coupled with DAD and ESI-MS

Using the HPLC/DAD/ESI/MS method, the qualitative and quantitative analysis of senkyunolide A (SA) in the rhizomes of Ligusticum chuanxiong (Rhizoma chuanxiong; CX) and roots of Angelica sinensis (DG) was established. As a result, it was found that SA is a characteristic standard compound for the quality evaluation and chemical differentiation between CX and DG. Methanol was chosen in the preparation of standard solutions and extraction of samples based on the stability data. The identity of SA in CX and DG was unambiguously determined based on the quasimolecular ions in ESI-MS. A comprehensive validation of the method, including sensitivity, linearity, reproducibility and recovery, was conducted using the optimized chromatographic conditions. The linear calibration curve was acquired with R2>0.999 and limit of detection (S/N=3) was estimated to be 12.5 mug/g. The reproducibility was evaluated by repeated sample injection and replicated analysis of samples with the relative standard deviation (RSD) value found within 0.68%. The recovery rates of SA varied within the range of 96.91-101.50% with RSD less than 2.38%. In the present work, the contents of SA were quantified within 3.94-9.14 mg/g and 0.108-0.588 mg/g for 12 batches each of CX and DG. The results demonstrated that SA is a useful standard compound for the quality evaluation and chemical differentiation between CX and DG. The analytical procedure is precise and reproducible and thus suitable for the analysis of a large number of samples.     

Chip-based nanoflow high performance liquid chromatography coupled to mass spectrometry for profiling of soybean flavonoids

In this work a chip-based nano HPLC coupled MS (HPLC-chip/MS) method with a simple sample preparation procedure was developed for the flavonoid profiling of soybean. The analytical properties of the method including the linearity (R(2) , 0.992-0.995), reproducibility (RSD, 1.50-7.66%), intraday precision (RSD, 1.41-5.14%) and interday precision (RSD, 2.76-16.90%) were satisfactory. Compared with the conventional HPLC/MS method, a fast extraction and analysis procedure was applied and more flavonoids were detected in a single run. Additionally, 13 flavonoids in soybean seed were identified for the first time. The method was then applied to the profiling of six varieties of soybean sowed at the same place. A clear discrimination was observed among different cultivars, three isoflavones, accounting for nearly 80% of total flavonoid contents, were found increased in the spring soybeans compared with the summer cultivars.     

Carrier-mediated liquid phase microextraction coupled with high performance liquid chromatography for determination of illicit drugs in human urine

A new method was developed for the analysis of illicit drugs in human urine by coupling carrier-mediated liquid phase microextraction (LPME) to high performance liquid chromatography (HPLC). By adding an appropriate carrier in organic phase, simultaneous extraction and enrichment of hydrophilic (morphine and ephedrine) and hydrophobic (pethidine) drugs were achieved. Effects of the types of organic solvents and carriers, the carrier concentration in the organic phase, the HCl concentration in the acceptor solution, the stirring rate, and the extraction time on the enrichment factor of analytes were investigated. Under the optimal experimental conditions, high enrichment factors (202-515) were obtained. The linear detection ranges were 0.1-10 mg L⁻¹ for the studied drugs. The limits of detection (LOD) at signal-to-noise ratio of 3 were 0.05 mg L⁻¹ for both morphine and ephedrine, and 0.02 mg L⁻¹ for pethidine. This method was successfully applied to analysis of ephedrine in real urine specimens, revealing that the determination of illicit drugs in urine was feasible.     

Microwave high performance liquid chromatography with UV-visible detection. Application to vitamins determination

The present work describes the first attempt to use microwave reversed phase high performance liquid chromatography (MW-HPLC) to carry out the separation of organic compounds. Biotin and riboflavin were selected for the characterization of the new separation technique. Additional vitamins (nicotinamide, pyridoxine and thiamine) were used as reference compounds. In order to perform the separation, a chromatographic column was placed inside a domestic microwave oven in a hanging position. The column particular location was an extremely critical point, since it precluded the actual power absorbed by the sample. In order to avoid magnetron damage, a heat well (i.e., water vessels) was used. Vitamins were detected using a UV-VIS detector. Results obtained showed that the application of microwave radiation, even at low power levels, gave rise to a significant modification in the characteristics of the chromatograms. It was found that retention times for biotin and riboflavin shortened as the power increased. Furthermore, the peak shape also changed, with the modification being more significant for the former vitamin than for the latter one. Furthermore, sensitivity also increased as the column was exposed to the action of microwave. Comparatively speaking, MW-HPLC was more efficient in terms of compound separation than when performed at room temperature or thermostatted at 45 °C HPLC. This was likely due to the combined action of a moderate and quick heating of the mobile phase with an increase in the analytes diffusivity caused by the radiation.     

柱前衍生-高效液相色谱法同时测定血清中氨基酸类及单胺类神经递质

以邻苯二甲醛（o-phthalaldehyde，OPA）为衍生试剂，建立了柱前衍生-高效液相色谱（HPLC）同时测定血清中氨基酸类神经递质牛磺酸（Tau）、谷氨酸（Glu）、甘氨酸（Gly）、γ-氨基丁酸（γ-GABA）和单胺类神经递质多巴胺（DA）含量的分析方法。血清与乙醇以1：2的体积比混合，进行蛋白质沉淀后离心，取其上清液，氮吹至近干。前处理后的样品与OPA进行柱前衍生，衍生化产物采用Luna 5u C18色谱柱（250 mm×4.6 mm，5 μm）分离，以柠檬酸-乙酸钠缓冲溶液（pH 3.73）为流动相A、乙腈为流动相B进行梯度洗脱，流速为1.0 mL/min，柱温为30℃，检测波长为338 nm。5种神经递质在各自范围内线性关系良好（r²≥0.9866），检出限为0.10~0.40 μmol/L，不同加标水平下目标物的加标回收率为87.57%~115.31%，相对标准偏差均低于7.80%。方法操作简单，灵敏度高，精密度、线性关系和回收率等方法学指标较好，可实现血清中氨基酸类及单胺类神经递质的同时检测。     

Sensitive determination of ethosuximide in human fluids by electromembrane extraction coupled with high performance liquid chromatography ultraviolet spectroscopy

Ethosuximide (ETX) is a common antiepileptic drug in the first line of absence epilepsy. In this study, for the first time, an economical and efficient electro-membrane (EME) method for determination of ETX in a complex biological matrix using HPLC-UV has been developed. Factors affecting conventional EME were evaluated. 1-Octanol was immobilized in a polypropylene membrane and a voltage of 35 V was applied between two platinum electrodes for 15 min. The pH of acceptor and donor phases for ionization of ETX was adjusted to 13 and 11, respectively. Under optimal microextraction conditions, the enrichment factor was 21.02 and the linear range of ETX was 0.25 to 8.00 μg/mL with an acceptable R² ≥ 0.9986. Inter-day and intra-day precision and accuracy of the suggested method were calculated with RSD < 9.5% and relative error <7.0%, respectively. The mean relative recovery of ETX in the human saliva and plasma samples was 81.68% and 74.47, respectively; while limit of detection and quantification concentrations were 0.08 and 0.25 μg/mL, respectively. Furthermore, to evaluate the application of the method, plasma and saliva samples of volunteers administering a single dose of ETX were analyzed successfully by EME-HPLC-UV method.     

高效液相色谱-串联质谱法同时测定食品中五种黄色化工染料

采用高效液相色谱-串联质谱法(HPLC-MS/MS)建立了食品中非法添加的碱性橙、碱性嫩黄、酸性橙I、酸性橙II和酸性黄36这5种黄色工业染料的定量定性分析方法。使用Agilent ODS C18分离柱(50 mm×2.0 mm, 1.8 μm),以5 mmol/L乙酸铵水溶液(0.1%甲酸)-乙腈(3:2, v/v)为流动相,流速为0.3 mL/min。采用电喷雾离子化源,以多反应监测(MRM)方式分别在正、负离子模式下进行检测。在最佳检测条件下,得到了较宽的线性范围和较低的定量检出限。碱性橙和碱性嫩黄的线性范围均为5.0～80.0 mg/L;酸性橙I、酸性橙II及酸性黄36的线性范围均为10.0～160.0 μg/L。食品中碱性橙、碱性嫩黄、酸性橙I、酸性橙II及酸性黄36的定量限分别为20、20、40、40、40 ng/g。该方法重现性较好,保留时间和峰面积的相对标准偏差分别不大于0.50%和2.14%。本研究还测定了鸡肉、豆制品和黄鱼中添加的5种化工染料,回收率在79.8%~95.2%之间,结果令人满意。     

Simultaneous determination of four 5-hydroxy polymethoxyflavones by reversed-phase high performance liquid chromatography with electrochemical detection

Accumulating evidence has suggested the potential health-promoting effects of 5-hydroxy polymethoxyflavones (5-OH-PMFs) naturally existing in citrus genus. However, research efforts are hampered by the lack of reliable and sensitive methods for their determination in plant materials and biological samples. Using reversed-phase high performance liquid chromatography (HPLC) equipped with electrochemical (EC) detection, we have developed a fast and highly sensitive method for quantification of four 5-OH-PMFs, namely 5-hydroxy-6,7,8,3′,4′-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone, 5-hydroxy-6,7,4′-trimethoxyflavone, and 5-hydroxy-6,7,8,4′-tetramethoxyflavone. The method was fully validated in terms of linearity, accuracy and precision. The limit of detection (LOD) was determined as being between 0.65 and 1.8 ng/mL (ppb), demonstrating an over 160 times higher sensitivity in comparison with the previously reported method using UV detection. The recovery rate of the method was between 96.17% and 110.82%, and the precision for the retention times and peak areas was all below 13%. The method was successfully used to quantify 5-OH-PMFs with a wide range of abundance in the citrus products and preparations, such as orange juice, citrus peel, and dried tangerine peel. The quantification method for 5-OH-PMFs developed herein could be useful for the nutritional and pharmacological studies of these compounds in future.